Solar furnace to keep race for hydrogen running hot

Is this a peek at the future of energy? This artist's impression shows a giant solar water-splitting array announced last week by a team from the University of Colorado Boulder.

The engineers' plan uses a huge array of mirrors to focus the sun's power like a giant magnifying glass and use it to split water into oxygen and hydrogen.

Sunlight would be focused at a point atop a central tower that could be hundreds of metres tall, generating temperatures up to 1350 °C. That would heat a reactor containing metal oxides, causing them to release oxygen atoms and leaving them hungry to replace that lost oxygen. Steam – also generated by the sun's heat – would then be pumped through the reactor. Oxygen from the water molecules bonds with the metal oxides, leaving behind precious hydrogen gas.

Some other water-splitting methods require alternating temperatures, making them less efficient. "One of the big innovations in our system is that there is no swing in the temperature," says Charles Musgrave, one of the project's leaders. "The whole process is driven by turning a steam valve either on or off."

It could be a while yet, though, before the technology and others like it get off the ground.

"Are we going to see much within the next five years? No," says David Hart of Imperial College London, an expert in sustainable energy systems. "Is [a hydrogen-fuelled economy] a viable proposition? Absolutely. There are already a lot of nice ways to make hydrogen: what we need now is a way to integrate the system into our current electrical grid."

One example of such efforts to make the grid more flexible are community grids.

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